A case of intestinovesical fistula secondary to leukemic infiltration is described. The patient was known to have chronic lymphocytic leukemia and had been receiving chemotherapy fo ten months. She presented complaining of nausea, vomiting and vague abdominal pain. She initially denied genitourinary tract symptoms, although admitting urinalysis revealed pyuria, hematuria and bacteriuria. Urine cultures repeatedly grew E. coli despite broad spectrum antibiotic therapy. She eventually developed fecalant material in her urine and pneumaturia. Cystoscopy revealed a fistulous tract. At surgery an ileovesical fistula was found and histopathology showed lymphocytic leukemic infiltration. Intestinovesical fistulas are uncommon. Congenital, traumatic, inflammatory and solid neoplastic etiologies are well established in the literature. No previous cases have been attributed to hematologic malignancies. Since higher remission rates and longer periods of remission are being achieved with chemotherapy, and since fistula symptomatology may present quite subtly, awareness of this association may expedite diagnosis.